The current tire pressure gauges available on the market are of two types, one of which is the pointer-type gauge having a switch, while the other is a scale-ruler type. The latter type has a small size and an inside space without switching means. In measuring a tire pressure, the gauge inlet is pressed against the nozzle of the tire valve and the pressure reading is taken immediately; upon the gauge inlet being removed from the tire valve nozzle, the pressure will also be removed simultaneously, and the scale-ruler will return to "zero"position.